Towards a Precision Measurement of the Lamb Shift in Hydrogen-Like Nitrogen
Measurements of the 2S 1/2-2P 1/2 and 2S 1/2-2P 3/2 transitions in moderate Z hydrogen-like ions can test Quantum-Electrodynamic calculations relevant to the interpretation of high-precision spectroscopy of atomic hydrogen. There is now particular interest in testing calculations of the two-loop self-energy. Experimental conditions are favorable for a measurement of the 2S 1/2 - 2P 3/2 transition in N 6+ using a carbon dioxide laser. As a preliminary experiment, we have observed the 2S 1/2 - 2P 3/2 transition in 14 N 6+ using a 2.5 MeV/amu foil-stripped ion beam and a continuous-wave CO2 laser operating on the hot band of 12C16O2. The measured value of the transition centroid, 834.94(7) cm-1, agrees with, but is less precise than theory. However, the counting rate and signal-to-background ratio obtained indicate, that with careful control of systematics, a precision test of the theory is practical. Work towards constructing such a set-up is in progress.
KeywordsInteraction Region Laser Line Proportional Counter Lamb Shift Intersection Angle
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